The hottest nano silica improves the properties of

Nano silica improves the performance of starch textile size

Abstract using nano silica to improve starch size, the principle of nano silica improving the wear resistance of starch size film is analyzed through experiments. The treated nano silica (same as vk-sp30f) particles were added to the starch slurry to prepare a film, and the effect of the content of nano silica (same as vk-sp30f) particles on the wear resistance of the slurry film was tested by a wear resistance tester. At the same time, the apparent morphology and wear mechanism of the slurry film were characterized by AFM, SEM and video zoom microscope. The results show that the size film of the mixed size added with an appropriate amount of nano silica (same as vk-sp30f) has better wear resistance than that of the pure starch size film, and when the content of nano silica (same as vk-sp30f) is 3%, the wear resistance of the mixed size film is the best

the size quality is the main factor that determines the warp sizing quality, and the size film wear resistance is one of the important indicators to detect the size quality. At present, starch, PVA and acrylic size are mainly used in the market. Among them, starch is widely used in warp sizing because of its rich resources, low price, good adhesion to natural fibers, less environmental pollution and other advantages, but its performance is not satisfactory. In order to further improve the quality of the slurry, nano materials are added to the slurry to produce "nano slurry", that is, inorganic fillers are dispersed in the organic polymer slurry in nano size to form organic and inorganic nano composite slurry, but there are few reports on this aspect. In this paper, nano silicon dioxide (the same as vk-sp30f) is used as filler and added into starch slurry to make slurry film. The wear resistance of the slurry film is tested on a wear-resistant testing machine. The micro surface morphology of the slurry film is observed by means of SEM, and the mechanism of nano materials to improve the wear resistance of the slurry film is analyzed, in order to expand the application of nano materials in the slurry

1 test part

1.1 raw material

nano silica (the same as vk-sp30f), particle size less than or equal to 35 nm, purity greater than or equal to 99.5%; Sodium hexametaphosphate, analytically pure,; Tb2225 modified starch, moisture less than or equal to 1.410%, ash less than or equal to 0.35%, protein less than or equal to 0.55%

1.2 instrument

electronic analytical balance, ab2042n, METTLER TOLEDO instruments (Shanghai) Co., Ltd; Ultrasonic cleaning machine, sj1200, 33 kHz, Shanghai Jingjie ultrasonic equipment manufacturing Co., Ltd; Zweigle wear tester, G552, Germany; Scanning electron microscope (SEM), quanta200, Fei company of the Netherlands; Video zoom microscope, DZ3, union company of Japan; Atomic force microscope (AFM), cspm3000, Guangzhou Benyuan nano instrument company

1.3 sample preparation

dispersion process: in order to reduce the agglomeration of nanoparticles, sodium hexametaphosphate is used to treat the surface of nano powders. Control the mass fraction of Nano-SiO2 in the slurry film to be 1%, 2%, 3%, 4%, 5% and 6% respectively. Weigh the nano-SiO2 with different mass (the same as vk-sp30f), add an appropriate amount of sodium hexametaphosphate, put it into deionized water, and disperse it with ultrasonic for 60 minutes, so as to break the aggregate, form a relatively stable nano-SiO2 water dispersion system, and make the suspension. Mixing process: weigh the starch and nano SiO2 Aqueous Suspension in proportion, prepare a mixing solution with a content of 6%, stir it at the speed of 120 rpmin, heat it up and boil it to 95 ℃, and keep it warm for 1 h, so that the starch can be fully gelatinized

film making process: when the fully gelatinized slurry is cooled to about 50 ℃, measure 400 ml, pour it on the glass plate, and dry it naturally under the condition of temperature 20 ℃ and humidity 65%. Balance for 24 hours under constant temperature and humidity for testing

1.4 performance test

cut the slurry film into 220 mm long strips with a width of 10 mm, and test it on G552 wear resistance tester. During the test, 800 mesh sandpaper is selected, the pressurized mass is 250 g, and the friction times are 1000. Each serous film was tested 10 times. Finally, use the formula to calculate the abrasion of each sample: g = (M0 - M1) ps

where G is abrasion; M0 is the mass of the sample before grinding; Early to early active M1 is the mass of the sample after grinding; S is the wear area. The smaller the wear value is, the better the wear resistance is

2 results and discussion

2.1 wear performance

with the increase of the content of nano silica (the same as vk-sp30f), the wear of slurry film decreases first and then increases. When the content of nano silica (same as vk-sp30f) is less than 3%, the wear decreases with the increase of nano silica (same as vk-sp30f); When the content of nano silica (the same as vk-sp30f) is 3%, the wear reaches the lowest, which is 0.511 mgpcm2; When the content of nano silica (the same as vk-sp30f) is greater than 3%, the wear increases gradually. This shows that an appropriate proportion of nano SiO2 can effectively improve the wear resistance of the slurry film

the content of nano silica (same as vk-sp30f) will affect the wear resistance of the slurry film, which may be due to the flocculent and quasi granular structure of nano SiO2, small particle size, large specific surface area, high surface energy, serious lack of coordination on the surface, easy to bond with the hydroxyl group on the starch macromolecule, and improve the bonding force between molecules; At the same time, due to the small size effect and macro quantum tunneling effect of nano silica (the same as vk-sp30f), it has a siltation effect, which can go deep into the unsaturated bond of the polymer chain and interact with the electron cloud of the unsaturated bond, so as to improve the wear resistance of the slurry film. However, too much nano silica (with vk-sp30f) will weaken the interaction between starch macromolecules and weaken the interface between starch molecules and nano SiO2, which will reduce the wear resistance of the slurry film and the soul performance of all components. At the same time, nano silica (the same as vk-sp30f) is easy to accumulate on the worn surface during the friction process. In the wear test of slurry film, some nano SiO2 particles contained in it fall off directly or accompanied by wear debris, but due to the physical adsorption in the migration process, they accumulate between the friction sample and the wear part, which can play a lubricating role. When the surface enriched nano silica (same as vk-sp30f) is not saturated, the anti-wear effect increases with the increase of SiO2 content. When the surface enriched nano silica (same as vk-sp30f) reaches the saturation value, it has little effect on the friction performance

2.2 characterization analysis

2.21 analyze the surface morphology of the slurry film before wear with AFM. Use the contact mode of AFM to scan the surface of the slurry film before wear. The starch film containing 3% nano silica (the same as vk-sp30f) showed uniform and irregular bulges on the surface. This is because the pure starch slurry film is formed by the entanglement of Starch Chain macromolecules with a single structure, so the film-forming structure is relatively uniform and the surface is relatively flat; The starch film containing 3% nano silica (the same as vk-sp30f) contains nanoparticles, which are coated by starch macromolecules and evenly dispersed in the film, and then combined with starch macromolecule chains to form a three-dimensional shape, which greatly improves the strength of the film and improves its wear resistance

2.22 analyze the surface morphology of slurry wear with a video zoom microscope. Observe the samples with a video zoom microscope. Fang xpressn lux, which uses coaxial illumination, will be the first to land on Cadillac XTS models sold to China to obtain the surface photos of slurry wear marks. The pure starch slurry film has obvious scratches and furrows, and there are also a large number of flake adhesive peeling signs, showing typical adhesive wear characteristics; The scratches and furrows on the surface of starch paste film containing 6% nano silica (same as vk-sp30f) are more obvious, but only a small amount of small granular adhesion and spalling, showing typical abrasive wear characteristics. In contrast, on the surface of starch paste film containing 3% nano silica (same as vk-sp30f), whether it is scratches, furrows or adhesive wear. According to the analysis of the above phenomena, when the pure starch slurry film is in contact with the abrasive, under the action of normal stress and tangential stress, the surface material takes the lead in plastic deformation and micro fracture. In the friction process, its environmental protection benefit is 10 points significant, and it separates from the matrix to form wear particles, which mainly shows the characteristics of adhesive wear; The slurry film containing 6% nano-SiO2 has agglomeration due to the high content of nano particles, which increases the volume of SiO2 particles, even the size is no longer nano-sized, and the wear debris containing nano particles transferred and accumulated to the surface during the friction process, and the scraping of the friction surface also increases, which increases the wear volume, mainly showing the characteristics of abrasive wear; When the content of nano SiO2 is appropriate (3%), it is evenly dispersed in the starch matrix and forms a strong interface with the matrix. In addition, the hardness of nano silica (with vk-sp30f) itself is very large. After filling starch, the surface hardness of the slurry film is increased, and the ability to resist adhesion wear and abrasive wear is improved

2.23 analyze the worn surface morphology of the slurry film by SEM. Put the worn sample into the vacuum coating machine for gold plating, and then observe the microstructure of the worn surface of the sample by SEM. The three slurry film surfaces after wear are arranged in a similar layer or scale shape, and the direction is parallel to the abrasive friction direction, showing the contact (surface) fatigue wear characteristics. The influence of nano silicon dioxide (the same as vk-sp30f) on the wear resistance of starch slurry film, because the strength of pure starch slurry film is relatively low, and it is easy to produce fatigue under the repeated action of abrasive, so a large number of scale peeling and pitting traces can be seen in SEM photos. When the nano material particles are added in excess (6%), some particles will agglomerate, making the slurry film structure have a source of stress concentration, that is, structural defects, It has become the source of fatigue wear cracks, that is, the peeling off of wear debris, but not all nanoparticles are agglomerated, so the fatigue wear degree of the slurry film is lighter than that of pure starch. Adding an appropriate amount of (3%) nanoparticles can make the structure of the slurry film denser and improve the strength. Even under the repeated action of the changing stress of the abrasive, the slurry film is not easy to produce microcracks, but only squeeze the surface material of the slurry film to both sides to produce grooves, It is not easy to produce wear debris, so large plastic deformation is reflected in SEM photos

it should be pointed out that in the actual wear phenomenon, several forms of wear usually exist at the same time, and one kind of wear often induces other forms of wear after it occurs, but different conditions change, resulting in different primary and secondary wear. Therefore, when combined with photo analysis, the analysis is mainly aimed at the most important wear characteristics

3 conclusion

1) nano silica (the same as vk-sp30f) as filler can effectively improve the wear resistance of starch paste film

2) when the content of nano silica (the same as vk-sp30f) is 3%, the wear resistance of the corresponding slurry film is the best, because at this time, a strong interface bonding can be formed between the nano filler and the starch matrix

3) the microstructure and friction surface of composite slurry film were studied by AFM, video zoom microscope and SEM respectively. The wear resistance data were consistent with the analysis of photos. (end)